The wave length of the photons also goes into it yes. I’d have to look up the precise formula. But it’s basically larger aperature -> smaller angle of separatio

The wave length of the photons also goes into it yes. I’d have to look up the precise formula. But it’s basically larger aperature -> smaller angle of separation. Longer wavelengths -> larger angle of separation. From a physics point of view there really isn’t much difference between light and radio waves. Both is just em radiation. But the absorption by matter (well really gas, there is nothing else) changes with wavelength too. And you’d optimize the ccds for whatever you want to look at. So that would be the primary consideration and keep in mind these things tend to also be build as tech demos (which also means you typically don’t get to realize all design capabilities in action). So “because it’s the most we could get away with” is a reasonable reason